package labels

import (
	"context"
	"database/sql"
	"fmt"
	"time"
)

// Record is one stored template row; JSON holds the Template document.
type Record struct {
	ID        int64     `json:"id"`
	Name      string    `json:"name"`
	Kind      string    `json:"kind"`
	ProfileID *int64    `json:"profile_id,omitempty"`
	StockID   *int64    `json:"stock_id,omitempty"`
	JSON      string    `json:"json"`
	IsDefault bool      `json:"is_default"`
	UpdatedAt time.Time `json:"updated_at"`
}

// Repo accesses the label_stocks and label_templates tables. Same shape as the
// QSL template repo it is modelled on — the label designer is that feature's
// smaller sibling and the storage questions were settled there.
type Repo struct{ db *sql.DB }

func NewRepo(db *sql.DB) *Repo { return &Repo{db: db} }

// ── stocks ──────────────────────────────────────────────────────────────

// Stocks lists every stored label stock, oldest first (the seeded Brother rolls
// keep their familiar order at the top).
func (r *Repo) Stocks(ctx context.Context) ([]Stock, error) {
	rows, err := r.db.QueryContext(ctx, `SELECT id, json FROM label_stocks ORDER BY id`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []Stock
	for rows.Next() {
		var id int64
		var doc string
		if err := rows.Scan(&id, &doc); err != nil {
			return nil, err
		}
		var s Stock
		if err := parseStock(doc, &s); err != nil {
			continue // one corrupt row must not hide the rest
		}
		s.ID = id
		out = append(out, s)
	}
	return out, rows.Err()
}

// SaveStock upserts one stock (ID 0 creates) and writes the id back.
func (r *Repo) SaveStock(ctx context.Context, s *Stock) error {
	if err := ValidStock(*s); err != nil {
		return err
	}
	doc, err := encodeStock(*s)
	if err != nil {
		return err
	}
	now := time.Now().UTC().Format("2006-01-02T15:04:05.000Z")
	if s.ID == 0 {
		res, err := r.db.ExecContext(ctx,
			`INSERT INTO label_stocks (name, json, created_at, updated_at) VALUES (?,?,?,?)`,
			s.Name, doc, now, now)
		if err != nil {
			return fmt.Errorf("insert stock: %w", err)
		}
		s.ID, _ = res.LastInsertId()
		return nil
	}
	_, err = r.db.ExecContext(ctx,
		`UPDATE label_stocks SET name = ?, json = ?, updated_at = ? WHERE id = ?`,
		s.Name, doc, now, s.ID)
	return err
}

// DeleteStock removes a stock. Templates pointing at it keep their design and
// fall back to "pick a stock" in the editor (the FK nulls the reference).
func (r *Repo) DeleteStock(ctx context.Context, id int64) error {
	_, err := r.db.ExecContext(ctx, `DELETE FROM label_stocks WHERE id = ?`, id)
	return err
}

// SeedStocks inserts the builtin rolls when the table is empty — first run, or
// an operator who deleted everything and wants the presets back gets them by
// emptying the table.
func (r *Repo) SeedStocks(ctx context.Context) error {
	var n int
	if err := r.db.QueryRowContext(ctx, `SELECT COUNT(*) FROM label_stocks`).Scan(&n); err != nil {
		return err
	}
	if n > 0 {
		return nil
	}
	for _, s := range BuiltinStocks() {
		st := s
		if err := r.SaveStock(ctx, &st); err != nil {
			return err
		}
	}
	return nil
}

// ── templates ───────────────────────────────────────────────────────────

const tplCols = `id, name, kind, profile_id, stock_id, json, is_default, updated_at`

// ListFor returns the templates visible to a profile (its own plus shared),
// defaults first.
func (r *Repo) ListFor(ctx context.Context, profileID int64) ([]Record, error) {
	rows, err := r.db.QueryContext(ctx, `SELECT `+tplCols+` FROM label_templates
		WHERE profile_id = ? OR profile_id IS NULL
		ORDER BY is_default DESC, id DESC`, profileID)
	if err != nil {
		return nil, err
	}
	return scanRecords(rows)
}

// List returns every template (no active profile yet).
func (r *Repo) List(ctx context.Context) ([]Record, error) {
	rows, err := r.db.QueryContext(ctx,
		`SELECT `+tplCols+` FROM label_templates ORDER BY is_default DESC, id DESC`)
	if err != nil {
		return nil, err
	}
	return scanRecords(rows)
}

// Get returns one template.
func (r *Repo) Get(ctx context.Context, id int64) (Record, error) {
	row := r.db.QueryRowContext(ctx, `SELECT `+tplCols+` FROM label_templates WHERE id = ?`, id)
	return scanRecord(row)
}

// Save upserts a template (ID 0 creates); the id is written back.
func (r *Repo) Save(ctx context.Context, rec *Record) error {
	if rec.Name == "" {
		return fmt.Errorf("template name required")
	}
	now := time.Now().UTC().Format("2006-01-02T15:04:05.000Z")
	if rec.ID == 0 {
		res, err := r.db.ExecContext(ctx, `INSERT INTO label_templates
			(name, kind, profile_id, stock_id, json, is_default, created_at, updated_at)
			VALUES (?,?,?,?,?,?,?,?)`,
			rec.Name, rec.Kind, nullID(rec.ProfileID), nullID(rec.StockID), rec.JSON,
			boolInt(rec.IsDefault), now, now)
		if err != nil {
			return fmt.Errorf("insert label template: %w", err)
		}
		rec.ID, _ = res.LastInsertId()
		return nil
	}
	_, err := r.db.ExecContext(ctx, `UPDATE label_templates
		SET name = ?, kind = ?, profile_id = ?, stock_id = ?, json = ?, updated_at = ?
		WHERE id = ?`,
		rec.Name, rec.Kind, nullID(rec.ProfileID), nullID(rec.StockID), rec.JSON, now, rec.ID)
	return err
}

// Delete removes a template.
func (r *Repo) Delete(ctx context.Context, id int64) error {
	_, err := r.db.ExecContext(ctx, `DELETE FROM label_templates WHERE id = ?`, id)
	return err
}

// SetDefault marks one template as the default FOR ITS KIND within its profile
// scope: printing asks for "the QSO label" and "the address label" separately,
// so the two defaults must not compete.
func (r *Repo) SetDefault(ctx context.Context, id int64) error {
	tx, err := r.db.BeginTx(ctx, nil)
	if err != nil {
		return err
	}
	defer tx.Rollback() //nolint:errcheck
	var kind string
	var profileID sql.NullInt64
	if err := tx.QueryRowContext(ctx,
		`SELECT kind, profile_id FROM label_templates WHERE id = ?`, id).Scan(&kind, &profileID); err != nil {
		return err
	}
	if profileID.Valid {
		_, err = tx.ExecContext(ctx, `UPDATE label_templates SET is_default = 0
			WHERE kind = ? AND (profile_id = ? OR profile_id IS NULL)`, kind, profileID.Int64)
	} else {
		_, err = tx.ExecContext(ctx, `UPDATE label_templates SET is_default = 0 WHERE kind = ?`, kind)
	}
	if err != nil {
		return err
	}
	if _, err = tx.ExecContext(ctx, `UPDATE label_templates SET is_default = 1 WHERE id = ?`, id); err != nil {
		return err
	}
	return tx.Commit()
}

// ── scanning helpers ────────────────────────────────────────────────────

type rowScanner interface{ Scan(dest ...any) error }

func scanRecord(row rowScanner) (Record, error) {
	var rec Record
	var pid, sid sql.NullInt64
	var def int
	var updated string
	if err := row.Scan(&rec.ID, &rec.Name, &rec.Kind, &pid, &sid, &rec.JSON, &def, &updated); err != nil {
		return rec, err
	}
	if pid.Valid {
		v := pid.Int64
		rec.ProfileID = &v
	}
	if sid.Valid {
		v := sid.Int64
		rec.StockID = &v
	}
	rec.IsDefault = def != 0
	rec.UpdatedAt, _ = time.Parse(time.RFC3339, updated)
	return rec, nil
}

func scanRecords(rows *sql.Rows) ([]Record, error) {
	defer rows.Close()
	var out []Record
	for rows.Next() {
		rec, err := scanRecord(rows)
		if err != nil {
			return nil, err
		}
		out = append(out, rec)
	}
	return out, rows.Err()
}

func nullID(p *int64) any {
	if p == nil || *p == 0 {
		return nil
	}
	return *p
}

func boolInt(b bool) int {
	if b {
		return 1
	}
	return 0
}